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This is for an offshore installation, IEC world. There are 4 gas turbine generators (4x33%) connected to a 6.6kV switchboard. The generators are high resistance grounded (20A per generator). It is a 3 Ph, 3 wire system Now regarding the connection of the resistors to the installation structure...

This is for an offshore installation, IEC world. There are 4 gas turbine generators (4x33%) connected to a 6.6kV switchboard. The generators are high resistance grounded (20A per generator). It is a 3 Ph, 3 wire system Now regarding the connection of the resistors to the installation structure...

The battery and Charger System generally comes along with the DG set as a standard vendor design. Following is generally specified by customer: -the number of consecutive starting attempts -Input supply voltage/ frequency to the charger -any metering/ lamp requirement on the charger -cable...

Is it a Wellhead Platform?

Bill, The grounding conductor is for grounding Instrument equipment (DCS, Fire & Fas Panel etc.). Actually, a single core, 70 sq.mm. cable (EPR Insulated) runs across the room. Individual grounding conductor (16 sq.mm, EPR )from each Inst. Equipment is connected to this 70 sq.mm. cable. A...

Hi all, With reference to an offshore project (IEC design), please inform if it is allowed to run PE (Protective Earth)Conductor on an Instrumentation cable Tray. The electrical power system is a 415V solidly earthed. The installation is an Instrumentation Technical room where it is required to...

Does IEC allow protection of more than one motor by one common breaker? I have come across a vendor drawing for a 'Davit' where there are two motors (one for hoisting and the other for slewing, both around 1 hp). And both these motors are protected by one common breaker. Is it ok?? IEC...

Hi Jerryjointer, If cables are laid in a trifoil formation (in a 3 phase system), then the induction effect should mutually get cancelled and there should be no induced voltage.

I posted this few days back but received no reply in the forum. Trying my luck again.... Spec. of one of the projects I am working requires that "Armour of all single core AC power cables shall be grounded at one end only”. I understand it is to do with circulating current but can't visualize...

Spec. of one of the projects I am working requires that "Armour of all single core AC power cables shall be grounded at one end only”. I guess it is to do with circulating current but can't visualize real problems for power cables. The project comprises of 6kV and 400V system and both systems...

Yes, I was talking about the cable from the primary wye side neutral to ground. The 30A ground fault current value through this cable is driven by the resistor put at the secondary delta corner. One would assume that the voltage drop across the resistor during fault would keep the primary...

A 6.6kV system is fed by 6.6kV generators, the generator neutrals are ungrounded. However, the 6.6kV bus is grounded by a grounding transfomer. The grounding transformer is primary star and secondary open delta with a resistor connected at the open delta to limit the gound fault current to 30A...

HI 00123456, Yes, you are correct. I'm talking about Motor Operated Valve. I should've expnaded it earlier. A single 480V supply goes to the actuator of the valve within which there are circuits for forward-reverse operation. I was refering to the single 480V supply breaker. Thanks,

Hi 00123456, Each MOV is protected by a 40A breaker. Considering the MOV size and conductor size, is the breaker rating OK per NEC? Normally a size 12 conductor should not have more than 20A breaker but is it true for MOV application?

Hi All! I have MOVs rated at 2290VA (3ea.) and 4410VA (4ea.), all 3 phase. MOVs are fed from a 480V, 3 phase panel. The MOVs are protected by a 40A breaker (short circuit protection only) and conductor size is 3C,#12. Could you please suggest 1.if the breaker is sized correctly as per NEC. 2...

There is a system where two transformers are connected in series. There is an existing transformer of 150 kVA (480V/4.16kV) in an offshore platform. This transformer feeds a new platform at 4.16kV through subsea cable and connects to a new transformer of 200kVA ,4.16kV/480V. (I have no idea why...

Per IEC 60092 "Electrical Installation on Ships", following is the recommended bending radius: Upto 1kV - Cable Dia (D) ? 25.0 mm –Unarmored and unbraided cables = 4D Armored and braided cables = 6D Cable Dia (D) > 25.0 mm –Unarmored and unbraided cables = 6D Armored and braided cables = 6D

try this link http://www.allaboutcircuits.com/vol_2/chpt_9/12.html

you can see the following link from ABB. They call these 'RI' Inverse curves. These curves are shown at fig. 39,page 72 of the pdf doc. But it doesn't tell you what RI stands for...

There is a software "Electric Power Quicksize" available form caterpillar which may be helpful. http://www.cat.com/cda/layout?m=37508&x=7